This invention relates in general to magnetic pulse welding techniques for permanently joining two metallic components, such as a pair of structural components for a vehicle frame assembly. In particular, this invention relates to an improved method and apparatus for performing a magnetic pulse welding operation that automatically and co-axially aligns the two components relative to one another and to a magnetic pulse welding inductor prior to full energization of the inductor for improved control of the magnetic pulse welding process.
Magnetic pulse welding is a well known process that can be used to permanently join two metallic components, such as a pair of structural components of a vehicle frame assembly. Typically, a magnetic pulse welding operation is performed by initially disposing the first and second components in an axially overlapping relationship. When so disposed, a portion of the first component axially overlaps a portion of the second component. An electromagnetic inductor is provided for generating an intense magnetic field within or about the axially overlapping portions of the first and second components. When this occurs, a large pressure is exerted on one of the first and second components, causing it to move toward the other of the first and second components at a high velocity. If the electromagnetic coil is disposed about the exterior of the two components, then the outer component is deformed inwardly into engagement with the inner component. If, on the other hand, the electromagnetic coil is disposed within the interior of the two components, then the inner component is deformed outwardly into engagement with the outer component. In either event, the high velocity impact of the first and second components, as well as the large pressures exerted thereon, cause the two components to become permanently joined together.
In order to insure that the two components are properly joined in this manner, it is important that they be co-axially aligned prior to energization of the electromagnetic coil. This is done to insure that a uniform annular gap is provided between the two components when they are subjected to the intense magnetic field. If a non-uniform gap is provided between the two components when they are subjected to the intense magnetic field, the some portions thereof may not achieve the necessary high velocity impact that is necessary to cause permanent joining of the two components. Traditionally, such co-axial alignment has been accomplished by mechanical fixtures that physically engage the two components and support them in the desired manner. However, such fixtures have been found to be relatively difficult to set up and maintain, particularly when the two components are relatively large or heavy. Thus, it would be desirable to provide an improved method and apparatus that automatically and co-axially aligns two components prior to full energization of the magnetic pulse welding inductor to provide for improved control of the magnetic pulse welding process.